Basically all Most units are in the Trunk area there is a most test
point under the dash. (on the under dash board drivers panel in
most US Cars I heard they moved it to the glove on some) There is a picture
of this panel and the Most Hub in the link supplied below.
The Most Bus is a Serial line any break in it and nothing in it works.
Fiberoptic lines can be checked/traced by shinning a light source
in one end and seeing it come out the other.
Most test point
http://www.e90post.com/forums/showthread.php?t=347222